A self-sensing active constrained layer damping treatment for a Euler - Bernoulli beam

In a self-sensing active constrained layer (SACL) damping treatment, the piezoelectric constraining layer is used simultaneously as both a sensor and an actuator. A variational formulation of ACL damping treatments has shown that an ACL damping treatment using a self-sensing and actuating piezoelectric element as the constraining layer in combination with rate of strain feedback as the control law will ensure that the power dissipated by the active damping always remains positive. This eliminates a major mechanism for system instability. Implementing this self-sensing actuator (SSA) as the constraining layer is made possible through the use of a bridge circuit that subtracts the strain signal from the actuator control voltage in the piezoelectric constraining layer and also differentiates the strain voltage in order to obtain the desired control law. An analytical model for ACL has been developed that can be used to predict theoretically the performance of a SACL damping treatment for a Euler - Bernoulli beam. A series of experiments studying the frequency response of an SACL test beam was performed and the results compared with the theoretical model. This theoretical model predicted the frequency of the first- and second-mode responses of the experimental beam very accurately and predicted the damping of these responses well. Therefore, this comparison indicated that the analytical model is capable of accurately predicting the frequency responses of beams treated with SACL.